Overview
The NCP1217AP65G, produced by onsemi, is an advanced PWM controller designed for high-performance AC/DC converters. It is an enhanced version of the NCP1203-based controllers, offering improved features such as high drive capability, internal ramp compensation, and built-in overvoltage protection. This controller is housed in either an SO-8 or PDIP-7 package and operates at a fixed frequency of 65 kHz. It is particularly suited for applications requiring low part-count and high efficiency, such as AC/DC adapters, TV power supplies, and telecom DC-DC converters.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Oscillation Frequency | 58.5 | 65 | 71.5 | kHz |
| Maximum Duty-Cycle | 69 | 74 | 80 | % |
| Peak Current Capability | 500 | mA | ||
| Internal Soft-Start Time (NCP1217A Only) | 1.0 | ms | ||
| Internal Temperature Shutdown | 150 | °C | ||
| No-Load Standby Power | Very Low | |||
| Package Types | SO-8, PDIP-7 |
Key Features
- Current-Mode Control with Adjustable Skip-Cycle Capability: Provides excellent input audio-susceptibility and inherent pulse-by-pulse control.
- Internal Ramp Compensation: Prevents subharmonic oscillations in continuous conduction mode designs.
- Auto-Recovery Internal Output Short-Circuit Protection: Disables output pulses and enters a safe burst mode during overcurrent conditions, auto-recovering once the fault is cleared.
- Internal 1.0 ms Soft-Start (NCP1217A Only): Ensures a smooth startup sequence.
- Limited Duty-Cycle to 50% (NCP1217A Only): Enhances control over the switching cycle.
- Full Latchoff if Adjustment Pin is Brought High: Permanently shuts off the device if the adjustment pin is raised above 3.1 V.
- Extremely Low No-Load Standby Power: Reduces power waste during light load conditions.
- Internal Temperature Shutdown: Protects the device from overheating.
- Direct Optocoupler Connection: Simplifies the feedback loop design.
- Internal Leading Edge Blanking: Improves noise immunity.
- SPICE Models Available: For transient and AC analysis.
Applications
- High Power AC/DC Converters for TVs, Set-Top Boxes, etc.: Ideal for high-power consumer electronics.
- Offline Adapters for Notebooks: Suitable for portable power supplies.
- Telecom DC-DC Converters: Used in telecommunications equipment.
- All Power Supplies: General-purpose use in various power supply designs.
Q & A
- What is the primary function of the NCP1217AP65G?
The NCP1217AP65G is a PWM controller designed for high-performance AC/DC converters, offering features like current-mode control, internal ramp compensation, and overvoltage protection.
- What are the available package types for the NCP1217AP65G?
The NCP1217AP65G is available in SO-8 and PDIP-7 packages.
- What is the operating frequency of the NCP1217AP65G?
The NCP1217AP65G operates at a fixed frequency of 65 kHz.
- How does the NCP1217AP65G handle overcurrent conditions?
The device disables output pulses and enters a safe burst mode during overcurrent conditions, auto-recovering once the fault is cleared.
- What is the purpose of the internal ramp compensation in the NCP1217AP65G?
The internal ramp compensation prevents subharmonic oscillations in continuous conduction mode designs.
- How does the NCP1217AP65G reduce no-load standby power?
The device skips unwanted switching cycles at low power levels, reducing power waste during light load conditions.
- What is the significance of the adjustment pin (Pin 1) in the NCP1217AP65G?
The adjustment pin allows for adjusting the skipping peak current and can be used to permanently shut off the device if raised above 3.1 V.
- Does the NCP1217AP65G generate acoustic noise during operation?
No, the NCP1217AP65G ensures noise-free operation by skipping cycles at low peak currents.
- What are some typical applications of the NCP1217AP65G?
Typical applications include high power AC/DC converters for TVs and set-top boxes, offline adapters for notebooks, and telecom DC-DC converters.
- Is the NCP1217AP65G Pb-free?
